Government intervention in the management of Northern Rock is universally regarded as a stain on British banking and monetary policy. The Bank of England's loan has reached £21bn, which is almost a fifth of Northern Rock's total liabilities. Alistair Darling, the chancellor, has said he expects the bank's directors to come up with proposals by February to end its reliance on government support.

But what is the rush? Is there a serious threat to Britain's public finances? Is a large sum of public money at risk?